where do i include the string library in my C++ header file

Question

My simple class won't compile in Visual Studio. It worked before I added the string company member and the getter method getCo() to it. I think I need to put #include the string standard library somewhere but I am not sure where. Any idea where? In my header file, I have:

#pragma once
#ifndef ENGINEER_H_
#define ENGINEER_H_

class engineer {
    int years;
    string company;
public:
    engineer(int years);
    ~engineer(void);
    int getYears();
    string getCo();
};

#endif ENGINEER_H_

And in my CPP file for the definition of the class, I have:

#include "StdAfx.h"
#include "engineer.h"

engineer::engineer(int y, string c){
    years = y;
    company = c;
}

engineer::~engineer(void) {
}

int engineer::getYears() {
    return years;
}

string engineer::getCo() {
    return company;
}

Answer 1

Put it in the header file, and prefix your usage of string with the namespace std.

Header:

#include <string>

class engineer
{
   std::string company;
};

In the implementation file (.cpp) you can prefix the names or have a using directive.

Implementation:

using namespace std;  // using directive, no longer need to use std::

Avoid putting the using directive in a header file, as that pollutes the global namespace and can cause problems with naming collisions in other libraries you may wish to use.

Answer 2

Put it in the header file, after the include guards:

#include <string>
using std::string;

This way, it will also be available for your cpp file, and you don't have to include it again.

BTW, the #pragma once and #ifndef ENGINEER_H_ serve the same purpose. You can have only one of them. Code generated by VC use the #pragma, which is shorter and doesn't add a definition, so that's what I'd use (no harm if you leave both, though).